Help modding Super-T amp and switching PSU...

[003]

All right, I am going to mod my Sonic Impact Super-T amp, based on these mods:
Quote:

1) Replace the input caps. Nice film caps here will help a lot. e.g Solen or Jantzen. 2) Replace the onboard electrolytic caps with Panasonic FM series or other good low ESR caps. The Pannies are inexpensive and work really well, fast and good sounding. This would be for the amp decoupling as well as in the power supply. 3) Add a good 100uF cap on the power jack. This will help lower noise coming from the switch mode power supply. 4) Maybe remove the reverse polarity protection diode. That will give a 0.6V boost, Can't hurt. 5) Add a stiffener cap. 10,000uF. Gives a tighter, stronger bass and wider sound stage. Use to taste, a lot of guys don't like the tighter bass, better damping factor. 6) Better wire on the inputs and outputs. 7) Add a heat sink.

Since I am a noob, I need clarification on a few of these. BTW they were taken from this site:
http://www.michael.mardis.com/sonic/start.html

First when it is suggested to replace the input caps with good film ones, I do not know which caps are the input caps. I am guessing C11, C12, C21, C22 and possibly C31? Is that correct? If not, which ones are they and how many are there?

Next when it is suggested to add the 100uF cap to the power jack, what cap should I use for this? Panasonic FM? Where exactly would I add this cap, and where would the polarity of the cap come into play (as it would not be marked)?

Also, I have a question about removing the reverse polarity protection diode. I assume that is D8? Would it just be pulled out and I would be done, or would the spot where the diode used to be require a wire jumper? Also, wouldn't it be dangerous to remove it? Because the plug on the power supply is not polarized so would there not be a big risk there?

Finally, what is some good and inexpensive wire that I could replace the stock wiring with? The stock wire dosen't even have shielding.

Moving on to the switching power supply. I cracked it open and it has 5 electrolytic capacitors:

400v 82uF
50v 10uF
16v 1000uF (two of these)
16v 100uF

Would these all be good to replace with Panasonic FMs? Or would any of them be good candidates for a different type of capacitor (like tantalum or film, etc)?

Then there are two diodes, and they are positioned in such a way that I can not easily make out the values. They appear to read:
CT PR150
But that does not turn up any results on google (I might not be seeing all the characters). Does anybody know what these are?

Finally, there are two resistors:
gold, silver, blue green
gold, yellow, black, brown

The electrolytics, diodes and resistors are the only parts I would feel comfortable replacing and I want to replace them with high quality parts. Could you guys give me some suggestions on what to replace them with?

Also, are there any modifications that could be made to this power supply (like other than just replacing the parts with higher quality ones)?

IMPORTANT
I spoke with ericj and he told me that switching power supplies strike a delicate balance with the parts they use and their specific values, and that just replacing things with higher quality parts is not a good idea unless you know what you're doing. Can anybody else give some input on this?

 

[lextek]

I modded a basic SI T-amp using a Tweak kit from audio Magnus.
http://www.audiomagus.com/component/...art/Itemid,27/

In there download section you can see the install instructions. I am quite pleased with the results. I enclosed it in a "block" of zebrawood to dress it up.
Don't know if this helps you.

 

[cotdt]

my opinion? it's not worth it. it's easier to build a "high-end" T-amp from stratch via a 41Hz kit. actually some headphone amps like the CKKIII have the same output (~6W into 8ohms) as the T-amp but much better sound quality and much lower noise.

 

[003]

Quote:

Originally Posted by lextek /img/forum/go_quote.gif I modded a basic SI T-amp using a Tweak kit from audio Magnus. http://www.audiomagus.com/component/...art/Itemid,27/ In there download section you can see the install instructions. I am quite pleased with the results. I enclosed it in a "block" of zebrawood to dress it up. Don't know if this helps you.

But that is of course for the normal T-amp which is very different from the super t which has a different board layout and already higher quality parts.

cotdt:
I can't. Don't have the know how for that. And the Super-t has closer to 12-13w output. Not to mention I already own the super t and got it at a very good price.

Can anybody help me?

 

[dcheming]

I'm not familiar with the super-t, but if you can take some close up pictures of the board we could probably figure out which ones are the input caps.

If you're worried about the noise of a switching power supply why not just get a cheap linear, regulated power supply instead of modding the one you have?

I'll have to say though that I agree with cotdt in that it's not really worth it. Since you got your super-t for such a good deal have you considered selling it and using the money to buy an AMP6 kit? Even if you have average soldering skills the AMP6 isn't to bad to build or you could always get someone else to build it for you instead.

 

[003]

I want to keep the super-t and while I want to do these mods to increase quality, I also want to do it for a good time and learning experience as well. It is easily moddable and mod it is what I want to do. You can find pictures as well as a lot of info about the SI t-amps here:
http://www.michael.mardis.com/sonic/start.html

and here's a picture from that site:

Also where could I get some heatsinks that I could cut to size?

 

[dcheming]

Looking at the super-t schematic C21 and C22 are indeed the input caps.

Pretty much any little heat-sink would work for this project. Attaching it to the chip/board is going to be the hard part though. Maybe using some thermal epoxy to directly bond it to the chip would work, but I don't think it would hold for very long. You'll have to get creative with the attachment method.

 

[003]

I want to use a decent heatsink though, a slab of aluminum won't cut it for me because I'm just anal like that. I would love to find one that would fit decently or find one that I could easily cut to size. Where should I look for something like this? As for attaching to to the chip, I was planning on using this:
http://www.arcticsilver.com/ceramique.htm

There are also two parts inside the power supply which will need a new heatsink because to open it, the heatsinks that were on them had to be destroyed (it was so cheaply made, you couldn't open it without destroying them). The heatsink was also a piece of crap, just a thin slab of aluminum. The parts that used the heatsink were an IGBT and a schottky barrier rectifier.

Also since you are looking at the schematic, would you be able to answer any of my other questions regarding modding the amp? I know they are simple and could be answered by looking at the schematic, but I don't know how to read the schematic. I barely know what the symbols for a capacitor and a resistor are.

 

[ericj]

That's not an adhesive, it's just a synthetic grease with colloidal ceramic particles in it. the heatsink will slide off.

 

[003]

Oops, I linked to the wrong stuff. I meant this:
http://www.arcticsilver.com/arctic_s...l_adhesive.htm

 

[dcheming]

Quote:

Originally Posted by 003 /img/forum/go_quote.gif would you be able to answer any of my other questions regarding modding the amp?

About the reverse polarity protection diode, personally I wouldn't remove it. If you want more voltage to get to the chip then I'd get a different power supply instead.

Sorry, I'm not really the best person to comment on your remaining questions.